PROJECT SUMMARY/ABSTRACT The Imaging Facility (IF) at the West Virginia University Health Sciences Center (WVU HSC) is a shared resource comprised of the Microscope Imaging Facility (MIF) and the Animal Models & Imaging Facility (AMIF). The IF is requesting funds to purchase a single line Nikon A1R High Definition Multiphoton (A1R-HD MP) imaging system equipped with a resonant and galvanometer driven scan head with 3 gallium arsenide phosphide (GaAsP) detectors and 1 non-GaAsP detector. This microscope will be managed by the microscope facility, but will be physically housed in the animal imaging facility in order to facilitate live animal imaging experiments. The mission of the IF is to provide access to a full range of light microscopy tools, small animal imaging systems, image analysis applications, and expert assistance to research groups at WVU and across the state. West Virginia is an Institutional Development Award (IDeA) state, and the Imaging Facility has been consistently supported by several IDeA funding mechanisms (CTR, COBRE and INBRE). MP microscopy is a service that the Imaging Facility currently cannot provide, as we do not have a functional MP system on campus that is available to our users. The need for this instrument is demonstrated in this application with several NIH- sponsored projects, spanning multiple disciplines including tracking metastatic breast cancer infiltration into neuronal tissue, mapping migratory cortical interneurons within the developing brain in the absence of key signaling kinases, alterations in brain vasculature from chronic and acute neurodegeneration associated with stroke and Alzheimer?s disease, real-time tracking of macrophage/monocytes and their regulation of the tumor microenvironment, and the consequences of maternal environmental nanoparticle exposure on the developing fetus. The requested system will receive institutional support for up to 100% of the cost of the salaries for the MIF Technical Director and the AMIF Imaging Specialist and the service contract throughout the life of the instrument. The IF Director and Imaging Specialists together have 50 years of experience in biomedical imaging. They will ensure that the system is properly maintained and used to its best potential. The IF is dedicated to supporting the imaging-related research efforts across our university, and the purchase of a MP microscope is critical for supporting these projects, all of which have the goal of identifying targets for therapeutic intervention in patients suffering from injury or disease.